Acoustical partitions



Dec. 1, 1964 J. J. YOUNG ETAL ACOUSTICAL PARTITIONS Filed May 1, 1961 Jams J Vow/a,

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DONALD /V. HUGG/NS INVENTORS A T Tam/[rs United States Patent 3,159,235 ACtIaUEl'lClQAL PAl-i'il'ilill'id James J. Young, linger Johnson, and Ronald N. gins, all of Newark, Ulric, assignors to il wens tlorning Fiberglas Corporation, a corporation Delaware Filed May l, 1961, gear. No. 1%,5'83 ll Claims. ttCl. lei-33) This invention relates to a method and a material for absorbing sound and more particularly to partitions that have improved resistance to the transmission of sound from one side to the other.

Many sound transmission resistant materials and partitions in the past have relied on the analogy that sound transmission through the material is a conversion of the energy in the sound waves to energy of vibration of the partition which in turn is reradiated from the opposite side of the material. This theory leads to the use of large partitions of dense materials for a reduction in sound transmission because the more mass being vibrated the greater is the energy required to vibrate it, and consequently the greater the attenuation of the sound. Partitions or walls of thisztype are usually built of steel, concrete or other dense materials. Such materials, however, in addition to being highly resistant to the transmission of sound, readily reflect the sound waves impinging on them and are therefore not very absorbent. Conversely, the light, airy materials such as rigid boards of resin bonded mineral or cellulose fibers are very absorbent and only a small percentage of the sound impinging on them is reflected. However, because of their rigid but light, airy nature they readily transmit the sound with little attenuation. As another factor, the dense attenuating materials require a correspondingly heavy supporting framework in order to effect a safe structural installation. The material. of this invention overcomes these difficulties by being light, airy and sound absorbent but at the same time being quite resistant to the transmission of sound.

The partitions constructed between adjacent rooms in present day dwelling units usually comprise a series of vertical studs mounted between floor and ceiling plates with gypsum wallboard or rock lath nailed to the opposing faces. A finishing coating of plaster is frequently applied over the wallboard and then painted or in the so-callcd drywall construction the joints between adiacent sections of the wallboard are hidden by covering them with a thin coating of plaster after which the entire wall is painted. In either case open space exists within the partition between the wallboards. This open space provides an excellent reverberation chmber and when one face of the partition is vibrated by sound waves impinging thereon these vibrations are transmitted to the other face by drum-like action through air entrapped between the faces.

Recent experiments have shown that an excellent sound insulating wall can be constructed utilizing a lightweight, low density (for example about %5 pounds per cubic foot) flexible blanket of glass fibers loosely bonded together with a pair of adjacent air impervious septa mounted therein. because of the loose, open, flexible character of these fibrous blankets the sound waves can penetrate them to excite and vibrat the loosely bonded 7 individual fibers, thereby changing the sonicenergy into energy of vibration which is dissipated by vibration of the fibers.

The air impervious sound blocking septawithin the fibrous mass prevent the direct gaseous conduction of sound through the blankets by the air therein, making it necessary for the sound waves to vibrate the septa in order to transmit sound therethrough.

A preferred form of this sound barrier comprises a low density pack of fibrous glass adhered together with a suitable binder, such as a phenol formaldehyde resin. T his fibrous glass pack is adhered to an air impervious septum such as kratt paper. The pack is produced corninercially by collecting the glass fibers and a sufiicient amount of resin to bond them together on a forarninous conveyor. They are then carried by a conveyor through a curing oven where hot gases are blown through them to cure the resinous binder and hold the individual fibers securely in place. if the conveyor transporting the pack through the curing oven is made up of several individual sections each section can be cleaned before the resin binder thereon has cured. This is done by running the individual sections of the conveyor through a bath which will dissolve and remove the uncured resin binder.

After the resinous binder has been cured the pack is adhered to a suitable septum such as a continuous web of kraft paper. This is accomplished by coating one side of the kraft paper with hot asphalt as it is drawn from the storage roll andthen bringing the coated side of the paper into contact with the fibrous pack whereupon the asphalt adheres them together. also increases the resistance of the paper backing to the transmission of water vapor and other gases, thereby increasing its effectiveness as a sound blocking septum.

The blankets are installed in a folded condition with the fibrousrnaterial facing outward to readily receive the sound and the backing material in the middle to form a pair of sound blocking septa. The blankets are preferably installed with the se ta in only light contacting relationship so that if one of them is excited by sound waves impinging thereon, thcse vibrations will not be transmitted directly to the other septum. The vibrations in the excited septum will be dampened by its sliding contact with the adjacent one and by the vibration of the fibers adhered thereto by the asphalt. It is important that the blankets be installed in only light contacting association,acoustically independent from one another, so that they will vibrate independently and vibrations in one will not be effectively transmitted to the other. This acoustically separated installation prevents a direct transfer of sound and vibrations through the blanket A rather light, effective barrier, to the transmission of sound can be constructed by incorporating such an arrangement of sound control blankets in an ordinary partition such as are conventionally used between rooms in homes. These partitions are constructed of two inch by four inch studs set vertically between ceiling and floor plates and faced with gypsum wallboard or rock lath which is painted or plastered to provide a finished surface. Preferably the blankets are suspended in a folded condition from the ceiling plate in which condition full advantage can be taken of their limp flexible nature, which most effectively dampens out sound entering therein. They are installed so that the exposed surface of fibers in the blanket will lightly contact the backs of the wallboard facings and dampen any vibrations therein. Light contact between the surface fibers in the blanket and the wallboard facing is assured by utilizing a blanket that, in its folded condition, is slightly thicker than the width of the supporting studs and therefore projects outward beyond the studs before the wallboard facings are installed. Since there is no adherence of these, fibers to the back of the wallboard they can, in dampening vibrations, slide thereover as well as be vibrated. Because of the flexible nature of these blankets the vibrations of the surface fibers by the acoustically excited wallboards are dampened with-in the blankets and the magnitude of these vibrations is greatly reduced after passing to the opposite side of the blanket.

Some sound and vibrations maybe carried through the blanket by the air therein. However, the blankets This. coating of asphalt mitted on from it. Therefore airborne sound and vibratio-ns will not be transmitted directly to the opposing w-allboard but must result from a transfer from the noise source to the first wallboard, from the first wallboard to the first septum, thence to the second septum and from there to the second wallboard and finally into the room the listener or receiver is located in. All during this multiple transfer of the energy, the vibrations are subjected to the dissipation inherent in the transfer of energy from one membrane to another and to the damping forces that the fibers connected to or touching these membranes Will exert thereon. In addition the vibrations passing through the blanket excite the individual fibers and this energy is dissipated by the vibrations of these individual fibers. The resistance of a fibrous mass like these blankets to the flow of air therethrough will also aid in dampening out the sonic waves transferring the sound from the wallboards to the septa and vice versa. These sound control blankets prevent an efficient sonic coupling of the wallboards through the wall cavity thereby improving the sound attenuating characteristics of the partition.

Although a single sound control blanket within the partition will improve its sound transmission characteristics it is preferred that a double blanket be used so that the uncovered fibrous glass will contact both facings. Securement of the blankets to the studs will assure that the blankets are adjacent thereto and prevent sound leaks through the partition adjacent these studs. However, it is preferred that these blankets not be secured to these studs but be left to slide freely thereover to avoid any tendency for thesound blocking septa to freely transmit vibrations through the partition by vibrating as if they were drum heads.

Further increases in the attenuating characteristics of this type of partitions and other non-supporting walls can be obtained by slotting the individual studs as shown in US. Patent 2,922,201 so that sound cannot be transmitted directly from one face of the partition to the other through these studs. lotted studs also allow each face of the partition to vibrate independently thereby further increasing the effectiveness in reducing the transfer of energy through the partition. This combination of the sound control blankets and slotted studding effectively prevents the transfer through a partition of this type of a major portion of the noise incident upon one face thereof.

Although the use of sound control blankets has been described with particular reference to residential partitions in which wooden studs and gypsum wallboard facings are used, they have a multitude of other applications. They may be used alone or in combination with an appropriate facing as a dividing wall in a large room, double walls of brick, concrete, wood, glass, etc., to prevent the transmission of sound therethrough, or they may be used in numerous other applications where low sound transmission and a high absorption is required.

An object of this invention is to provide an improved combination of materials in a structural arrangement for attenuating sound.

Another object of this invention is to provide a novel economical wall construction adapted to providing excellent heat and sound insulating properties.

A further object of this invention is to provide a wall resistant to the transmission of sound which will absorb a large percenta e of the unreflected incident sound.

A further object of this invention is to provide a lightweight economical sound attenuating partition.

Still another object of this invention is to provide a new lightweight economical partition structure for dwelling units, which partition has eflicient acoustical and thermal properties wherein the acoustical properties embody the dampening of vibration of the facing members to present a solid thud-like sound rather than a ringing sound when one or both facing members are subjected to sharp blows, an efficient absorption of sound transmitted beyond the facing members, and a septum blocking of sound which might be transmitted beyond the first layer of acoustical material adjacent a vibrated facing member.

Other objects and advantages of this invention will become apparent when reference is made to the following description and drawings in which:

FIGURE 1 is a sectional view of a partition incorporating the sound absorbing blankets of this invention before the wallboard facings have been placed thereon;

FIGURE 2 is a sectional partially cutaway View of a completed partition more clearly illustrating the construction of the sound absorbing blankets and their association with the wallboard facings;

FIGURE 3 illustrates the use of these blankets to form a freely suspended sound absorbing and attenuating wall;

FIGURE 4 is a cutaway view illustrating a partition wh rein the studs have been modified to improve the sound attenuating characteristics of the partition;

FIGURE 5 shows another type of modified stud which may be utilized in partition to increase its sound attenuating properties; and

FIGURE 6 illustrates another modified stud that may be used to improve the sound attenuating characteristics of a partition.

Referring to FIGURE 1, the studs 11 are mounted on a horizontal fioor plate 12 and connected together at the top by a horizontal ceiling plate 13. The sound absorbent mineral fiber insulation 14 is suspended from the ceiling plate 13 and completely fills the space between the adjacent studs. This sound absorbent mineral fiber insulation is, in its preferred form, fibrous glass and is manufactured by collecting the freshly formed fibers and an organic resin binder on a foraminous collecting chain. it is cut to the proper width and a kraft paper septum for effectively blocking or reducing the transmission of sound is adhered to one side of it by asphalt which is applied to the kraft paper immediately before it contacts the fibrous glass. A preferred method of installing the sound absorbent blankets between the studs, is to first cut a paper backed blanket to a length at least as long as twice the height of the studs. They are then folded in two with the paper carrier being back-to-back to form a pair of sound blocking septa having the same width as the fibrous glass. The folded blankets are attached at the fold to the ceiling plank 1'3 by fastening means 17 such as nails, staples, etc., so that t e sound attenuating septa are in the middle and the sound admitting fibrous glass is on the outside. Because of their flexible charact-er the blankets will hang limply in place and be easily vibrated by sound waves incident thereon. This limpness assures that a large percentage of the vibrations will not be transmitted through the blankets but will be dissipated therein by vibration of the fibers and the septum facing. Since the fibrous glass and the septa are formed to the same width as the space between adjacent studs, there is a rather close fit between the sound absorbent blankets and the studs thereby minimizing the amount of sound energy that can be transmitted through the partition through openings immediately adjacent the studs. The loose ends of the folded blanket are then held in place adjacent the floor plate by fastening means such a nails, etc, passing through the fibers and septa and into the floor plates to prevent the blankets from becoming displaced such as by progressive creeping and correspondingly preventing the transmission of sound through those openings.

The folded fibrous glass blankets are made to be slightly thicker than the studs, thereby making it necessary to compress the surfaces when fastening the wallboards in place. This slight compression of the surfaces of the fibrous glass blanket by the wallboards assures that there is a light intimate association between the fibrous glass and the back of the wallboard. Because of this association, vibrations in the gypsum board resulting from voices in the room, someone playing a piano, or other sources are transmitted from the wallboard to the surface of the fibrous glass pack and dissipated therein. It is important and highly advantageous to have this resilient compression of the fibrous mass be light in order to dampen vibrations imparted thereto by way of the surface of the blanket. This compression of the blanket must be insufiicient to give the blanket a rigidity or integrity that will permit the transfer vibrations therethrough from one Wallboard to the other. This change of character generally occurs when the density of the blanket is about pounds per cubic foot or upwards therefrom. However, it is also dependent on how tightly the fibers are bonded to one another and the type and amount of resinous binder therein.

As shown in FIGURE 2, the wallboards, or rock lath are fastened to the floor and ceiling planks and studs to hold them in place. The intimate association of the surface of the fibrous glass blankets with these wallboards, which occurs because the fibrous glass sound absorbing blankets in their normal condition have a thickness slightly greater'than the distance between the insides of the .wallboards, imparts an improved more solid sound of quality to the partition. However, this slight compression of the surface of the fibrous glass blanket is purposely made to be insufiicient to force the sound blocking septa 16 together which would otherwise permit vibrations to be transferred directly from one to the other or to change the resonating frequency of the wallboard because of a spring-like push on the backside thereof. Because the septa 16 are not pushed together by the fibrous glass, but will vibrate independently without driving each other, it is necessary for sound in order to pass through the blanket to in turn drive each one of them separately.

Because the fibrous glass is also adhered to the septa,

vibrations in the septa will be dampened and dissipated by imparting mechanical motion to the fibrous glass thereby markedly reducing the sound transmission characteristics of the partition. If these septa were adhered together or were forced too tightly into intimate association with one another over a large portion of their surfaces, the sound waves upon striking and vibrating one of them would automatically, because of this intimate association, vibrate the second septum, causing them to vibrate as one, thereby decreasing their efiiciency for blocking sound transmission. However, by maintaining a looseness in their contact, they are made to vibrate somewhat independently so that the energy in the sound wave must first be suficient to activate one and then after passing therethrough, activate the other.

As illustrated in FIGURE 3, the sound absorbent blankets may be freely suspended over a wire or other horizontal support to form a sound absorbent'walldike structure which may be used to help acoustically isolate a noise source such as a particularly loud machine in a large open working area. To construct this lightweight, acoustical partition, a supporting wire 20 is strung between conveniently available walls or columns (not shown); The sound control blankets 21 are then folded with the facing septa on the inside and hung over the supporting wire. it is preferred that these sound control blankets extend all the Way from the ceiling to the floor to minimize leaks around them and make maximum use of the sound absorbing properties of these blankets. The blankets are suspended in side-by-side contacting relationship and if desired the septa of adjacent blankets may be fastened together to prevent adjacent blankets from becoming displaced or separated and permitting noise to leak between them. When such blankets are suspended in this manner,

the sound freely enters the lightweight porous fibrous mass and excites or vibrates the freely movable fibers thereby converting and dissipating the sonic energy as energy of motion in the fibers. By utilization of a limp hanging installation, the sound blocking septa in the center of the sound control blankets are independently vibrated thereby more effectively dissipating the sonic energy and preventing its transmission through the sound control blankets. Here again, the loose lightweight fibrous pack adhered to the septa, dampen vibrations of the septa to further reduce the sound transmission characteristics of the partition. By covering exposed surfaces of the fibrous glass blanket with a thin flexible film of, for example, polyethylene, Mylar, etc, a washability can be imparted to this wall. if the film is thin and flexible, e.g. 1-10 mils, it can be readily vibrated by the sound waves impinging thereon and will not reflect much of the incident sound and therefore will not greatly reduce the sound absorption characteristics of the blanket.

Further improvements in the sound attenuating characteristic of partitions incorporating vertical studding can be obtained by using a staggered stud arrangement where in two sets of 2" by 4" studs are mounted on a2 by 6" face plate so that alternate studs are fastened to opposing wallboards to provide an entirely independent set of studs as support for each wallboard facing. A similar improvement can be obtained by acoustically isolating opposite sides of the studs and the wallboard facings attached thereto by providing a single continuous slot 22 cut laterally through the stud for a major portion of its length as shown in FlGURE The cut is normally provided after the studs have been nailed in place between the floor and ceiling plates. The preferred method of cutting the slot is to use a hand circular saw and in a single pass to cut the slot for the entire length of the stud, leaving only a small section intact near the floor plate 23 and the ceiling plate 24 to maintain the integrity of the stud and provide a solid section for greater strength. The air space in the center of the stud eliminates trans mission through the partition of a major part of the solid borne vibrations and allows the wallboard facings to vibrate independently;

By the Way of example, tests have shown that a drywall partition constructed according to this invention incorporating the combination of'the sound control blankets with 2" by 4 slotted studs will prevent the transmission of sound incident on one face thereof as well or better than a 6" painted cement block wall. In addition, important economics result from the higher weight and improved heat insulating ability of the partition incorporating these sound control blankets. This large decrease in the amount of sound transmitted appears to result because, with partitions incorporating these sound control blanketswith associated split studs, essentially all major paths for the transmission of sound through the stud are at least partially blocked and most of the transmitted sound will pass through leaks in the partition such as where the sound control blankets do not contact the studs. Also, if the partition does not extend all the way to the roof, a large amount of noise will pass through the ceiling of the room containing the source, over the partition, and down through the ceiling into the room containing the receiver. Leaks of this type will substantially nullify any further increases in the sound attenuating characteristic of these partitions which might result from the addition of more sound absorbing material to the partiton.

FIGURE 5 shows a stud which has been slotted in a slightly different manner to provide improved acoustical properties somewhat similar to a stud slotted as illustrated in FIGURE 4 to reduce the conduction of vibrations directly throughthe stud. The slots in the studs 25 comprise a series of independent slots 27 in the center of the stud and another series of slots 23 on both sides of those in the center but disposed so that they overlap the spaces between the slots in the center and therefore require solid vibrations to follow a tortuous path in order to pass through the stud.

Still another arrangement of slots shown in FluURE 6 also aids in reducing the direct transmission of sound and vibrations through the stud. This stud 2-9 has a series of canted overlapping slots 3% extending over almost its full length. These slots are so located that any vibrations passing horizontally through the stud will intersect at least one of these slots. This arrangement of slots also aids in reducing tendencies toward bowing or buckling of the studs. These sound control blankets may also be used in partitions built with slotted metal studs or with special attachments fitted to the studs which will substantially reduce the direct transmission of sound through the studs.

Although this invention was described with particular reference to a loosely bonded fibrous glass blanket with a kraft paper backing, it is understood that blankets of rock or mineral wool, asbestos, wood fibers, etc., backed with a sound blocking septum such as a tar paper, metal foil, organic film, or a limp heavy fabric loaded with particles or clay etc., can be efiective as sound control members and utilized Within the scope of this invention. When these sound control blankets are installed between the sides of a double concrete block wall the resistance of the wall to the transmission of sound and heat is greatly improved. This decrease in the transmission of heat also reduces the amount of condensation on the wall. Further, decreases in the condensation can be obtained by sealing the top of the wall to prevent a chimney effect and drilling holes in the wall near the bottom. With this arrangement of openings hot air from the surroundings will, because of its lower density, replace the cooler air inside the wall and be trapped thereby increasing the temperature of the wall.

It is apparent, that within the scope of this invention, modifications and diilerent arrangements may be made other than are herein disclosed and the present disclosure is illustrative merely, he invention comprehending all variations.

We claim:

1. A room partition resistant to the transmission of sound comprising: a plurality of supporting studs; facings attached thereto to form the walls of said partition; sound control blankets freely suspended between said facings extending substantially the entire length thereof and having their edges in nonsecured co-linear relationship with said supporting studs; said sound control blankets comprising a layer of interbonded fibers adhered to a sound blocking septum that is substantially co-extensive therewith.

2. A lightweight partition with improved resistance to sound transmission comprising: a plurality of supporting studs; facings attached to opposing sides of said studs to form the walls of said partition, at least some of said studs being slot ed over a major portion of their length to separate them into substantially acoustically independent sections; said studs being posltioned so that one of said acoustically independent sections is positioned adjacent each facing; sound absorbent blankets suspended *etween said facings extending the entire height thereof and having their edges in substantially adjacent co-linear relationship with said studs; sound absorbent blankets comprising a layer of lightweight, interbonded fibrous material adhered to a flexible air impervious septum that is substantially co-extensive therewith the outer surfaces of said'fibrous material being in light intimate association with the back surfaces of said facings,

3. A partition resistant to the transmission of sound comprising: a plurality of vertical supporting studs; facings fastened to opposite sides of said partition; a pair of sound control blankets freely suspended be ween said facings extending the full height thereof with their edges in adjacent co-linear relationship with said supporting studs; said sound control blankets comprising a layer of lightweight, interbonded fibrous glass wool adhered to a flexible, substantially air impervious septum and being co-extensive therewith; said sound control blankets being suspended .in back-to-back relationship with said fibrous glass wool facing outward and having a total thickness slightly greater than the width of said studs whereby the surfaces of said blankets are slightly compressed during the installation of the facings establishing a light intimate association of said fibers with said facings.

4. A partition resistant to the transmission of sound comprising: a framework including a plurality of studs and supporting means engaging and maintaining said studs in fixed positions; facings fastened to opposite sides of said framework forming the walls of said partition; sound control blankets freely suspended within said framework etween said facings extending the entire height thereof and having their edges in adjacent co-linear relationship with said supporting studs while being free to slide thereover; said sound control blankets comprising a layer of interbonded fibrous glass wool having a density of from %5 pounds per cubic foot adhered to a limp sound blocking septum, and being co-extensive therewith; said blankets being suspended between said facings in back-to-back relationship with the fibrous glass wool faclug outward and the adjacent septa being free to slideover one another; the outer surfaces of said fibrous blankets being compressed by and in intimate association with said facings.

5. A lightweight partition resistant to the transmission of sound comprising: a framework including a'fioor plate, a ceiling plate, vertical supporting studs extending between said door and ceiling plates; facings applied to the two major surfaces of said framework; a vertical slot in the center of each of said supporting studs passing through all but the upper and lowermost sections thereof separating said studs into two substantially acoustically independent scctions each of said sections being positioned adjacent one of said facings; sound-control blankets freely suspended between said facings from said ceiling plate and fastened to said floor plate; said sound control blankets comprising a flexible layer of interbonded fibrous glass wool having a density of from %5 pounds per cubic foot adhered to a limp, substantially air impervious septum that is coextensive with said layer of fibrous glass wool; said'sound control blankets suspended between said facings in back-to-back relationship with said layers of fibrous glass wool facing outward in sound absorbing condition, and having their edges in adjacent co-linear relationship with said studs while being free to slide thereover; said installed blankets having an uncompressed total thickness greater than the distance between said facings.

6. A lightweight partition resistant to the transmission of sound comprising: a framework including, a floor plate, aceiling plate, supporting studs mounted between said floor and ceiling plates; wallboard facings fastened to both sides of said framework; each of said studs being slotted to acoustically isolate one facing from the other; a freely suspended interbonded 4-5 pounds per cubic foot fibrous mass filling the space between said wallboard facings; said fibrous mass being in two sections; each of said sections being adhered to one of two substantially air impervious septa positioned back-to-back within said partition; said septa being fastened to said floor and'ceiling plates and having a sliding contact with said studs; said fibrous mass in its as installed state having a width slightly greater than the distance between said facings whereby the surfaces of said fibrous mass adjacent said facings are compressed lightly to assure a light intimate association of said surface fibers with said facings; said compression being insufficient to force said septa into sound transmitting relationship.

7. A lightweight partition resistant to the transmission of sound comprising: a framework including, a floor plate, a ceiling plate, supporting studs extending between said floor and ceiling plates; facings fastened to the major surfaces of said framework on opposite sides thereof, said supporting studs in said framework having a slot passing substantially the entire length thereof for reducing the transmission of solid borne vibrations from one facing to the other through said studs and permitting each of said facings to vibrate substantially independently from the opposing one; a pair of substantially air impervious flexible septa positioned adjacent one another within said framework between each set of studs; each of said septa being fastened to said floor and ceiling plates and having its edges in substantially adjacent, co-linear relationship with said studs; 21 light-density interbonded blanket of fibers adhered to one surface of each of said septa and being essentially coextensive therewith; the opposite surface being free to slide over the adjacent septum; and the surfaces of said blankets touching said facings being compressed to establish a light intimate association be tween said fibers and said facings.

8. A partition resistant to the transmission of sound comprising: a framework including supporting studs and means for engaging and maintaining said studs in fixed position; each of said studs being slotted therethrough over a major portion of its length; facings fastened to 10 said framework to form the walls of said partition; sound control blankets comprising a flexible layer of interbonded fibers adhered to a flexible sound blocking septum freely suspended within said framework between said facings; said sound control blankets being suspended in back-toback relationship with the fibrous layer in contacting position with said facings, and the edges of said blankets being unsecured and extending in co-linear close abutting relationship with said supporting studs.

References Cited in the file of this patent UNITED STATES PATENTS 1,908,917 Phillips May 16, 1933 2,081,765 rudden May 25, 1937 2,081,952 Parkinson June 1, 1937 2,175,630 Kiesel Oct. 10, 1939 2,177,393 Parkinson Oct. 24, 1939 2,350,513 Leadbetter June 6, 1944 2,922,201 Baker Ian. 26, 1960 3,051,260 Eckel Aug. 28, 1962 FOREIGN PATENTS 614,404 Great Britain Dec. 15, 1948 

1. A ROOM PARTITION RESISTANT TO THE TRANSMISSION OF SOUND COMPRISING: A PLURALITY OF SUPPORTING STUDS; FACINGS ATTACHED THERETO TO FORM THE WALLS OF SAID PARTITION; SOUND CONTROL BLANKETS FREELY SUSPENDED BETWEEN SAID FACINGS EXTENDING SUBSTANTIALLY THE ENTIRE LENGTH THEREOF AND HAVING THEIR EDGES IN NONSECURED CO-LINEAR RELATIONSHIP WITH SAID SUPPORTING STUDS; SAID SOUND CONTROL BLANKETS COMPRISING A LAYER OF INTERBONDED FIBERS ADHERED TO A SOUND BLOCKING SEPTUM THAT IS SUBSTANTIALLY CO-EXTENSIVE THEREWITH. 